The present invention relates generally to bearing manufacture and structure, and in particular to plastic bearing and manufacture.
Plastic bearings provide an alternative to metallic counterparts where wet or harsh environments are encountered and where low maintenance is required. In food processing applications, plastic bearings operate without a grease lubricant as required in metallic bearings. Plastic bearings are more compatible for certain chemical applications relative to metallic bearings. Plastic components can out perform metallic components in many situations, especially in dirty, dusty and contaminated environments. Little or no lubrication is required as most parts made of industrial plastic have, to a limited extent, self-lubricating properties.
Many plastic components are inherently low friction materials. Some plastic bearing components are impregnated with a lubricant, e.g., oil. Oil impregnated plastics include pockets of oil imbedded in the plastic material. Upon machining to final form, some oil pockets are exposed and provide a limited source of lubrication. In particular, the amount of lubricant delivered is limited by the number of oil pockets exposed in machining the part. Eventually, use of the part exhausts the lubricant supply, and the part eventually fails.
Furthermore, plastic bearings must be of significant rigidity to carry a load during operation. As oil is impregnated into the plastic rigidity is lost, and loading capabilities diminish. In other words, a high concentration of lubricant lessens the compressive strength of plastics.
Similar considerations apply to other plastic devices such as plastic conveyors. A plastic conveyor includes a guide track and a chain carried thereon. Such plastic conveyors may be constructed of materials similar to the above-described plastic bearings and use of grease as a lubricating agent is undesirable in many applications. Further, load bearing capability is diminished when significant lubricant is impregnated into the plastic conveyor elements.
It would be desirable, therefore, to provide an alternate form of lubrication in a plastic products without packing grease into, for example, bearings or conveyor elements, and without sacrificing an ability to carry a significant load during operation.